EP0520623B1 - Lichtleitende Tafel zur Flächenbeleuchtung und Gerät zur Flächenbeleuchtung - Google Patents

Lichtleitende Tafel zur Flächenbeleuchtung und Gerät zur Flächenbeleuchtung Download PDF

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Publication number
EP0520623B1
EP0520623B1 EP19920304799 EP92304799A EP0520623B1 EP 0520623 B1 EP0520623 B1 EP 0520623B1 EP 19920304799 EP19920304799 EP 19920304799 EP 92304799 A EP92304799 A EP 92304799A EP 0520623 B1 EP0520623 B1 EP 0520623B1
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EP
European Patent Office
Prior art keywords
light
panel
face
guiding panel
plane
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Expired - Lifetime
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EP19920304799
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English (en)
French (fr)
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EP0520623A1 (de
Inventor
Nobuyoshi Tawara
Takeshi Kojima
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Nissen Chemitec Corp
T Chatani and Co Ltd
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Nissen Chemitec Corp
T Chatani and Co Ltd
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Publication of EP0520623A1 publication Critical patent/EP0520623A1/de
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0045—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide
    • G02B6/0046—Tapered light guide, e.g. wedge-shaped light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/004—Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles
    • G02B6/0043—Scattering dots or dot-like elements, e.g. microbeads, scattering particles, nanoparticles provided on the surface of the light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/0068—Arrangements of plural sources, e.g. multi-colour light sources
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0066—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form characterised by the light source being coupled to the light guide
    • G02B6/007—Incandescent lamp or gas discharge lamp
    • G02B6/0071—Incandescent lamp or gas discharge lamp with elongated shape, e.g. tube

Definitions

  • This invention relates to a light-guiding panel for back lighting of various types of apparatus equipped with liquid crystal displays, in particular, televisions, lap-top personal computers, word processors, computer game devices, etc.; or for a system for displaying various information or an advertisement; and further relates to a surface-lighting assembly with such a light-guiding panel.
  • Displays and analogous indication equipment provided with liquid crystal are characterised by low electric power consumption and small thickness. For such reasons they have hitherto been used as the displays of digital watches or clocks and electronic calculators, but recently they have started to be practically used instead of cathode ray tubes (Brown's tube), depending on recent explosive progress in thin membrane formation technics. Thus, it is presumable that liquid crystal displays will become the main image indicator in the near future.
  • a liquid crystal itself does not emit light, it is necessary to illuminate it from behind in order to visualize the images formed by fine liquid crystals.
  • a surface-lighting body made from single or plural (laminated) flat plate(s) made of polymethyl methacrylate (commonly called "acrylic plate”) with printed white dots on one or both of its surfaces) as light-scattering means.
  • the common plane light-guiding panel is thin, its thickness being insufficient to catch much of the light directed towards its edge surface of its edge, it is low in averaged luminance. Thus, it is only useful as a light-guiding panel for a black- and-white image.
  • a wedge-shaped light-leading panel as shown in Fig. 14 has been proposed.
  • it is necessary to increase enough the thickness of its base edge in order to increase the amount of incident light but this, on the contrary, makes larger the inclined angle of the slant surface so as to shorten the breadth of the light-guiding panel and, thus, only a narrow (up-to-down) image area can be obtained.
  • this confrontation of the two wedge-shaped light-guiding panels causes a defect that a brilliant line is seen along with the confronted line due to increase of light reflection at such confronted part and this defect can not be solved by decreasing the density of the dots at the confronted parts of the panels. Moreover, this defect can still not be solved even if the acute edges of the panels have been cut off as in Fig. 16, whereby therewill become visible a dark line instead of the brilliant line in the former case. Furthermore throughout any known light-guiding panels, there is a problem that the luminosity obtained is uneven.
  • DE-A-32 08 162 discloses the pre-characterising part of claim 1.
  • US-A-4 945 350 discloses a light guiding plate in which each of its faces has a concave portion in order to enhance uniformity of brightness. However, the shape of the face is not further explained or accurately described.
  • DE-A-40 08 953 discloses a light-guiding plate having a roughened light-emitting face with a narrow part-cylindrical concave middle portion continuously connected to two convex side portions.
  • the opposite, planar, reflecting face is also roughened.
  • a middle region of the light-emitting face or of the reflecting face has only a small degree of roughness. This is said to decrease the brightness in the middle so that uniform surface lighting may be obtained.
  • the object of the present invention is to provide a practical light-guiding panel having high averaged luminosity and broad image area in which the generation of the brilliant or dark line which is the defect of the known symmetrical wedge-shaped light-guiding panel is eliminated.
  • the present invention is further directed to the provision of a compact surface-lighting system by decreasing the weight and volume of the lighting body, not only accommodating the trend of the present era towards "light-thin-short-small” but also making it possible to set an IC (integrated circuit) substrate into the space thus provided by the minimization of the panel.
  • the present invention provides a light-guiding panel as set forth in claim 1.
  • section used hereinafter means vertical section.
  • Fig.1 is a schematic section view of the solid-type light-guiding panel according to the present invention.
  • Fig.2 is an explanatory section view of an example of a solid-type light-guiding panel of the present invention.
  • Fig.3 is an explanatory section view of another example of a solid-type light-guiding panel of the present invention.
  • Fig.4 is a section view of further example of a solid type light-guiding panel of the present invention.
  • Fig.5 is a section view of a surface-lightening body by composing an invented solid-type light-guiding panel according to the present invention.
  • Fig.6 is a plan view showing the positions at which the measurements of the luminosity were carried out.
  • Fig.7 is a partially cut-away section view of a surface-lighting body with an image indication system by composing an invented solid-type light-guiding panel according to the present invention.
  • Fig.8 is a partially cut-away section view of another surface-lighting body with an image indication system which is composed by a solid type light-guiding panel according to the present invention.
  • Fig.9 is a section and explanatory views of a quasi(pseudo )-symmetrical wedge-shaped light-guiding panel composed of four planes.
  • Fig.10 is an explanatory view showing the behavior of the light at the light-emission surface in a light-guiding panel composed of two planes intersected together.
  • Fig.11 is another explanatory view showing the behavior of the light, wherein the center of the light-guiding panel is a symmetrical concavity with two planes which is not tangentially adjoined thereto.
  • Fig.12 is a section and explanatory views of the behavior of the light at the light-emitting surface in a light-guiding panel composed of a concavity and a tangential plane adjoined thereto.
  • Fig.13 is another explanatory view and a section view showing the behavior of the light where in the case in which the light is emitted off from the plane face of the panel of Fig.11.
  • Fig.14 is a diagrammatic section view of known wedge shaped light-guiding panel.
  • Fig.15 is a diagrammatic section view of a symmetrical wedge-shaped light-guiding panel, wherein a pair consisting of two unit light-leading panels of Fig.14 are confronted each other at their sharp acute apexes.
  • Fig.16 is a similar figure with Fig.15, but in which each apex being cut away.
  • Fig.17 is a modification of the light-guiding panel of Fig.16 in which the confronted part of the both panels is rounded to a small circular arc.
  • Fig.18 is a diagrammatic section view of another surface lightening body with a hollow light-guiding panel according to the present invention.
  • Fig.19 is a diagrammatic section view of another hollow light-guiding panel according to the present invention.
  • Fig.20 is a partial section view showing the principle of the hollow-type light-guiding panel according to the present invention.
  • Fig.21 is another partial and enlarged section view showing the principle of the hollow-type light-guiding panel according to the present invention.
  • Fig.22 is a diagrammatic section view showing an example of the lighting body according to the present invention.
  • optical glass means property permeable to visible lights(of ca .400-700 nm of the wave lengths) without scattering. Naturally, since we have still no such material of 100% light permeability, this term may be regarded as synonymous with "clear” in our common sense.
  • the organic glass is desirable for carrying out the invention because it is not only light, of 1/2 or less in the specific weight than inorganic glass and hardly to be broken but also castable corresponds to the inner shape of the cast used.
  • any glassy materials including heterogeneous fine particles or fine bubbles such as opaque glass or foamed glass are improper as the material of the light-guiding panel, because although they transmit the incident light, but excessively attenuate the intensity of the light of incidence which is parallel to the faces of the plate.
  • concave face and concave-plane means that the shape of the section of the light-guiding panel along with its length or breath-wise direction is a shape in which a symmetrical circular arc or conical arc(such as a parabolic or an elliptic arc) contacts with or circumscribes with either the apexes A and E or the slants AC and EC in the two symmetric rectangular triangles (symmetric wedges) CBA and CDE on a common basic line B-C-D as shown in Fig.1.
  • a symmetrical circular arc or conical arc such as a parabolic or an elliptic arc
  • the face formed is any of symmetrically synthesized face (hereinafter called as "concave-plane") which is composed of asymmetric concavity and two planes tangentially adjoinded thereto.
  • the central concave portion (expressed by a solid line) is a circular arc, wherein the radius(R) of the tangential circle can be calculated according to the Formulae I, below, when the thickness and breadth of each symmetric wedge-shaped panel 2', 2" are a and b, respectively at the thinnest portion at the center is T.
  • any conical arc such as hyperbola or elliptic arcs, curves of trigonometric function, catenary(hyperbolic cosine curves), curves of cycloid, curves of trochoid, expornential curves,involute curves ,asteroid etc.,and therefore, we can freely select any curve as far as it is of symmetry, convex to downward and is one-dimensionally increasing function-wise curve(means the curve not having their maximum and minimum values between form the center (for example, the point C in Fig.1) to the circumscribed point).
  • the face synthesized from a centric circular arc face and peripheral tangential planes adjoined to the former(the concave-plane) is better in view of easiness in the design of the pattern to be printed which derives expected homogenity of the luminosity.
  • the one having a parabolic face as the concavity is preferable in viewpoints that higher and more averaged luminosity than corresponding face of a circular arc.
  • the entire concavity as shown in Fig.4 (in which the face is composed of a circular arc) is also preferable in view of effective utilization of the space surrounded by the points ABCA in this figure.
  • the face is entirely composed of a concavity or a synthesized from a concavity with the tangential plane(the concave-plane) and how to decide the numerical value of the curvature the shape of said concavity should be determined according to the characteristics to be expected for the light-guiding panel as the back light.
  • the distances C-G and C-F from the confronting apexes of the both triangles C to the points of the contact G and F with the curve 3(wherein this curve is explanatorily shown as a circular arc with a radius OH from the centric point 0) should be 1/10 or longer, preferably, 1/5 to 2/3, of the length of the slants CA and CE of the triangles CAB and CED. If the distance is less than 1/10 of the lengths of said slants,there can hardly be obtained desired homogenity in luminosity.
  • the concave-plane is generally provided at one side of the panel but the both sides of the panel may be composed of the concave-plane as shown in Fig.3, if desired.
  • the thicker of the thickness of the both sides composed of the concavity or the concave-plane the larger of the amount of the light to be crawled into the panel.
  • said thickness is large enough, particularly, so as to allow to hole through holes for disposing cold cathode discharge tube adjacent to the both sides of the panel.
  • the light-guiding panel according to this invention may be composed as a hollow body as in Examples 4 and 5 hereinafter set forth.
  • Such hollow panel not only has unexpectedly good performance irrspective of the existence of the intermediary air layer but also much lighter and easier to be prepared than the solid one.
  • the light-guiding panel of the present invention may be prepared by pouring a casting material such as methyl metacrylate into a mold assembled by easily-separable material such as polished stainless steel with the catalyst, heating for hardening, annealing, taking out the molded article from the mold, and then cutting and polishing the peripheral parts of the article, if need be.
  • a flat plate of organic or inorganic glass may be grind and polished so as to form necessary concavity or concave-plane, however, this is inferior than casting in the producibility.
  • polymethyl metacrylate resin may, theoretically, be molded by an injection molding since this resin has plasticity.
  • the light-guiding panel is formed as the hollow body, it can be made by bending or pressing acrylic plate at a temperature higher than its glass transition point in or with an appropriate shaping molds.
  • the above light-guiding panel according to the present invention is then processed to an aimed surface-lighting body by forming a reflecting face at the one side(generally at the flat face) of the panel by the attachment of a reflecting material such as a mirror or aluminum foil or by the deposition of fine silver particles through a silver mirror reaction or by spattering on the one side of the panel as well as a light-scattering plate arranged on the other face (mainly on the concavity or the concave-plane), and there are further provided fine dots with white paint at least at one face selected from the reflecting face and the light-scattering face (light-emitting face) of the light-leading panel.
  • the light-scattering plate may be apart from the convex face of the light-guiding panel as explained in the aftergoing Embodiment 1 (Refer to Fig.5.).
  • the complementary use of fine prismatic plate or Fresnel lens plate will be effective to improve the luminosity, but it has some defect whereby undesired glittering will be increased.
  • linear light source such as a fluorescent lamp or cold cathode discharge tube.
  • the latter is most desirable at nowadays because of its comparatively small diameter and large luminous energy per unit length, and of coolness when it is lightening (almost does not generate heat).
  • a white dotty light source such as crypton lamp, xenon lamp or halogen lamp etc. may also be available, but they are inferior as the light source than the linear light source because they must be used as a set of a number of unit lamp, generate heat and have a comparatively short life.
  • the thickness of the edges of the light-guiding panel is equal to or larger than the outer diameter of the light source.
  • the panel has(have)(a) large through hole(s) at the inside of its thick portion into which there can be is inserted a cold cathode discharge tube, maximum efficiency will be expected.
  • the outer diameter of cold cathode discharge tubes now marchandized is 3-8 m/m.
  • the inner diameter of the through hole(s) is(are) designed so as to exactly fit with the tube used, almost light energy from the source is incident into the inside of the light-guiding panel because there is few difference between the organic glass composing said light-leading panel and inorganic glass composing said discharge tube in their light refractive indexes.
  • the light-guiding panel of the present invention almost does not generate any brilliant line much different from known symmetrical wedge-shaped light-leading panel or a modification thereof composed of a synthesized concave-plane consisting from a concavity and planes which are not tangentially adjoined thereto. This remarkable difference can be explained as follow:----
  • the mechanism of the generation of the brilliant line by referring Fig.10. Namely, if the light-emitting face is a bent plane formed by crossing two planes as in Fig.9, the downward portion beneath symbols(face) AOB is the interior of the light-guiding panel and the upward portion above said symbols becomes air layer, and the incident rays from the edge face of the panel are emitted off from the interior of the panel (beneath the face AOB ) to the air layer (above said face AOB ).
  • the refracted light within ⁇ FOI are of a synthesized lights of the rays from the face AO with that of another plane face BO which is inclined to the face OA .
  • the intensity of the rays at this point 0 is the total of the rays from the plane faces AO and BO where its luminosity(cd( cd /m 2 )) is greater than the average luminosity of each face and equal to or smaller than the arithmetical total of the both as shown by the following Formula III.
  • Formula III Luminosity on the face OA ⁇ + Luminosity on the face OB ⁇ 2 ⁇ cd ⁇ Luminosity on the face OA ⁇ + Luminosity on the face OB ⁇
  • ⁇ FOI the luminosity of the light-emitting face within ⁇ FOI becomes remarkedly greater than those of the faces OA or OB whereby the brilliant line will be generated.
  • the groups of the rays(the luminous flux) have some breadth, therefore, a more brilliant line than the other faces but not focused is appeared along with the crossed bent plane.
  • the mechanism of the generation of a brilliant line in a face composed of a plane face OA and a concave face OB which are adjoined each other intermittent with a straight line may be presumable as similar as the above(6a)(cf. Figs.11 and 12). Namely,the emitted rays at the point 0 among the rays emitted from the plane OA off will be emitted as a refracted light within ⁇ FOE so long as the incident angle is smaller than the critical angle(i p ).
  • the luminosity of the light-emitting face within ⁇ FOI becomes remarkedly greater than those of plane face OA or concave face OB whereby the high brilliant line will be generated.
  • the light-emitting face is composed of a concave-plane in which the plane OA is tangentially connected to the concavity OB
  • the light-emitting face is composed of a plane and a tangential plane adjoined thereto at the junction 0 , any the brilliant line will be vanished.
  • this is generally applicable to any concave-plane composed of a circular arc or parabolic arc and planes tangentially connected to the arcs.
  • the mechanism explained in the above paragraph (6b) is on a case where the light-emitting face is a concave-plane and the light-reflecting face is a plane.
  • the emitting face and the concave-plane become the light-reflecting face(with a light-reflecting material such as mirror or the like).
  • the emitted rays(the luminous fluxes) will be incident into the light-leading panel again and re-emitted from the plane side through repeated refraction, transmission and reflection.
  • the rays once have converged to from the brilliant line are not entirely dispersed away through the above processes and emitted from the plane face as a somewhat vague brilliant line.
  • the light transmittability of light-leading panel is approximately proportion to the thickness y at the distance x from the edge face( AB or ED ) in Fig.1.
  • the thickness at the section y in the light-guiding panel defined according to the above paragraph(1b) is usually y > y' wherein y' is the thickness at the point x of the concave panel having the same curvature.
  • the light-guiding panel having a concave-plane face defined at the paragraph(1b) has greater light transmittability than that having a simple concave face, if the other conditions are the same. Therefore, if both the largeness and the maximum thickness are equal, the light-guiding panel of concave-plane type is better than that of the simple concave type.
  • the simple concave-type panel is preferable for disposing an IC substrate into the concavity as shown by the aftergoing Embodiments 2 and 3, the simple concave-type panel is preferable. As has previously been mentioned, through hole (s) excavated into the panel for disposing cold cathode discharge tube is(are) effective to utilize light from the light source without loss.
  • the hollow light-guiding panel acts so as to prevent the generation of the brilliant line as in the solid-type light-leading panel set-forth in the above.
  • the luminous flux L 1 which goes along with the axis leaks toward the outside of the system, but the other fluxes L 2 ⁇ L 4 are either directly reflexed at the inner face of the bottom wall 2e of the light-leading panel 2 (when it is greater angle than the critical angle; L 2 ), or collide with the light-scattering dots 5 , 5 ...
  • this surface-lighting body comprising of solid type light-guiding panel there is not arisen local concentration of luminous flux which cause the brilliant line because the light reflection or light emission face is composed of a symmetric concavity or concave-plane alike the solid-type one, irrespective of the presence of the inner air layer, and moreover, it is unexpected that there can hardly been seen depression in the luminosity which is presumable as the result of the total reflection caused by intermittence of a different refractive medium, that is, inner air layer 6.
  • the ray L 5 becomes parallel light to the plane portion 2e of 2 so that it does not contribute to the luminosity.
  • the concave face( 2a ⁇ 2c ) is used as the light emitting face as in the aftergoing Embodiment 4, the average luminosity becomes lower than that of the case, wherein the plane face 2e is used as in the after going Embodiment 6.
  • this hollow light-guiding panel is used as the surface lightening body.
  • the radius of the tangential circle was 35.63 cm from Formulae I.
  • the weight of known plane light-guiding panel was decreased down to about one-half.
  • this panel was 205.5 g which corresponds to about 52.7 % by weight as compared with that of flat acrylic plate of 10 mm thickness(380.8 g).
  • an IC substrate 8 of 3.75 mm of the thickness, 100 mm of the breadth and 200 mm of the length could be inserted into the concavity as in Fig.7.
  • Another acrylic light-guiding panel having circular arc face at its one-side and of 8 mm thickness in the edge face, 160 mm in the width, 200 mm in the height and 2 mm thickness at the central portion was prepared and was dotted on its concave face, followed by sticking up a scattering sheet on its plane face and a reflecting sheet on its concave face, respectively.
  • the luminosity measured was 2050 cd /m 2 with 85 % homogenity. And, there could be disposed an IC substrate 8 of 3.75 mm, 100 mm and 200 mm, its thickness, breadth and length, respectively, into the concavity.(See Fig. 8).
  • the weight of this light-guiding panel was 152.3g correspond to just one-half of plane light-guiding panel having equal largeness(weight 304.6 g).
  • the weight of plane light-guiding panel could be decreased down to one-half by this changing to concave shape.
  • Fig.22 is a diagrammatic section view of a hollow-type surface-lighting body according to another embodiment of the present invention.
  • the light-guiding panel 2 as the main part of this equipment is composed by assembling a concave-plane member 2A consisting of the central part with circular arc 2a and two tangential planes adjoined thereto 2c , 2c and the side parts with circular arcs 2d , 2d , and a plane member 2B consisting of the plane central parts 2e and the both side parts 2d' , 2d' with same circular arc.
  • the inner curvature formed by parts 2d and 2d' was destined so as to fit that of the tubular light source 4 by this combination.
  • the thickness of both members 2A and 2B was 1 mm. Dotting 5 , 5 ... by white paint was applied to the inner surface of the central part 2e of the member 2B .
  • a light reflecting sheet 3 was sticked on the backside the plane central part 2e of the member 2B .
  • a light scattering plate 7 was equipped at the front position of the central part of the member 2A and attached to the sheet 3 with an adhesive. And the both members were fixed with a light reflecting tape 3' by encompassing the both edges of the sheet 3 and the plate 7 at their both sides 2d and 2d' , respectively.
  • this surface-lighting body was as follows:--- Breadth(A):160 mm Length(Perpendicular toward the paper):220 mm Thickness(b):10 mm
  • two cathode discharge tubes 4 , 4 were set into the side parts 2d - 2d' , 2d - 2d' , as in this Fig.22, and the luminosity was measured in the same manner as described in Embodiment 1 to give 1500 cd /m 2 of the averaged luminosity and 88 % of homogenity in the luminance.
  • dots for diffuse reflection were printed onto the inner face of the concave-plane member 2A . Then, the luminosity and homogenity were increased up to 1800 cd /m 2 and 91%.
  • Embodiment 5 a light reflecting sheet 3 was sticked up to the concave-plane member 2A and further a light-scattering plate 7 was disposed to the plane member 2B . There was obtained similar result comparable with Embodiments 1 to 3, of the average luminosity 2100 cd /m 2 with 93 % homogenity.
  • Example 4 further disposed a fine prismatic plate, called "SOLF"(furnished by Sumitomo Three-M Co., Ltd.) under the light-scattering plate 7 so that the prismatic face looks upward.
  • the luminosity obtained was 2050 cd /m 2 with 85 % average homogenity.
  • SOLF was disposed under the light-scattering plate 7 to give 2400 cd /m 2 of the average luminosity with 91 % homogenity.
  • the plane member 2B was substituted with SOLF which looks upward.
  • the luminosity observed was 2400 cd /m 2 with 89 % homogenity.
  • the present invention has resulted in the resolution of the generation of the brilliant line in the known symmetric wedge-shape light-guiding panel whereby there can be provided a new light-guiding panel having an averaged high luminosity with high homogenity and a broad image are as well as new surface-lighting body derived from said new panel.
  • the present invention is not only effective in deadweight of the light-guiding panel to about one-half or more as compared with that of known plate-like light-guiding panel but also contribute to downsizing of image-expression system by disposing an electronic device such as IC substrate into the space of its concavity.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)
  • Liquid Crystal (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Claims (9)

  1. Lichtleiterplatte (2) zur Flächenbeleuchtung, wobei die Platte (2) aus einem optisch transparenten Material besteht und aufweist: eine lichtreflektierende Fläche (SR), eine gegenüberliegende lichtemittierende Fläche (SE), und Enden, aus denen das Licht längs einer Lichtachse parallel zur Platte (2) gerichtet werden kann, wobei die Platte (2) in der Mitte auf halbem Weg zwischen ihren Enden am dünnsten ist, wobei mindestens eine der Flächen (SR, SE) eine synthetisch hergestellte Fläche ist, die aus zwei ebenen Abschnitten besteht, die an einen mittleren konkaven Abschnitt angrenzen, um somit eine symmetrische Schnittform in einer Schnittebene zu liefern, die die Lichtachse umfaßt und senkrecht zur Platte (2) verläuft, wobei ein Umriß der symmetrischen Schnittform umfaßt: (i) zwei gegenüberliegend angeordnete gerade Linien (AG, EF), die mit Bezugnahme auf die Lichtachse geneigt sind, und die sich jeweils in einer Richtung von einem äußeren Endpunkt (A, E) an einem Ende in Richtung eines mittleren Punktes (C) erstrecken, und (ii) einen bogenförmigen Abschnitt (GHF), dessen Enden (G, F) an die entsprechenden Enden (G, F) der geneigten geraden Linien (AG, EF) angrenzen, dadurch gekennzeichnet, daß:
    die geneigten geraden Linien (AG, EF) tangential zum bogenförmigen Abschnitt (GHF) verlaufen;
    der Umriß einen geometrischen Zustand aufweist, der wie folgt definiert wird: vorausgesetzt, daß die folgenden Punkte gegeben sind, d.h., ein mittlerer Schnittpunkt (C), in dem zwei hypothetische Linien (GC, FC), die von den entsprechenden geneigten geraden Linien (AG, EF) aus verlängert werden, einander schneiden, und die entsprechenden Schnittpunkte (B, D) einer geraden Linie, die durch den mittleren Schnittpunkt (C) hindurchgeht und parallel zur Lichtachse verläuft, und der geraden Linien (AB, DE), die durch die entsprechenden äußeren Endpunkte (A, E) hindurchgehen und senkrecht zur Lichtachse verlaufen, dann ergeben zwei Paare von drei Punkten (CAB, CED) zwei hypothetische rechtwinklige Dreiecke (ΔCAB, ΔCED), die kongruent und spiegelsymmetrisch mit den gegenüberliegenden spitzwinkeligen Scheitelpunkten (C) angeordnet sind; und
    die Länge einer jeden hypothetischen Linie (GC, FC) nicht kleiner ist als 1/10 und nicht größer als 2/3 der Länge der Hypotenuse (CA, CE) eines jeden hypothetischen rechtwinkeligen Dreieckes (ΔCAB, ΔCED).
  2. Lichtleiterplatte nach Anspruch 1, bei der die Länge einer jeden hypothetischen Linie (GC, FC) nicht kleiner ist als 1/5 der Länge der Hypotenuse (CA, CE).
  3. Lichtleiterplatte nach Anspruch 1 oder 2, bei der der bogenförmige Abschnitt (GHF) eine Kurvenlinie ist, die ausgewählt wird unter:
       konischen Bogen, wie beispielsweise einem kreisförmigen Bogen, einem parabolischen Bogen, einem hyperbolischen Bogen, einem elliptischen Bogen, Kurven einer trigonometrischen Funktion, einer Kettenlinienkurve (hyperbolischer Kosinus), einer Zykloidenkurve, einer Trochoidenkurve, einer exponentiellen Funktionskurve und einer Evolventen.
  4. Lichtleiterplatte nach Anspruch 3, bei der die Kurvenlinie ein kreisförmiger Bogen oder ein parabolischer Bogen ist.
  5. Lichtleiterplatte nach einem der vorhergehenden Ansprüche, bei der die Platte (2) hohl ist.
  6. Lichtleiterplatte nach einem der vorhergehenden Ansprüche, bei der eine der Flächen eben ist.
  7. Lichtleiterplatte nach einem der vorhergehenden Ansprüche, bei der die lichtreflektierende Fläche (SR) mit weißen Punkten versehen ist.
  8. Lichtleiterplatte nach einem der vorhergehenden Ansprüche, bei der die Enden der Platte symmetrische Durchgangslöcher für das Aufnehmen von Kaltkatodenentladungsröhren aufweisen.
  9. Flächenbeleuchtungsbaugruppe, die eine Lichtleiterplatte nach einem der vorhergehenden Ansprüche aufweist.
EP19920304799 1991-06-27 1992-05-27 Lichtleitende Tafel zur Flächenbeleuchtung und Gerät zur Flächenbeleuchtung Expired - Lifetime EP0520623B1 (de)

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Application Number Priority Date Filing Date Title
JP18365991 1991-06-27
JP183659/91 1991-06-27
JP108969/91 1991-12-06
JP10896991 1991-12-06
JP78890/92 1992-02-28
JP4078890A JPH06102414A (ja) 1991-06-27 1992-02-28 面照明用導光板及び面型照明体

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EP0520623A1 EP0520623A1 (de) 1992-12-30
EP0520623B1 true EP0520623B1 (de) 1997-10-08

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KR100414882B1 (ko) * 1996-09-25 2004-05-31 삼성전자주식회사 광균일성을위한액정표시장치의백라이트구조
WO1998021520A1 (en) * 1996-11-14 1998-05-22 Antonio Michael Derose A light unit
JP2001215507A (ja) * 2000-02-04 2001-08-10 Sharp Corp 導光板およびそれを用いた面状光源、並びにそれを用いたバックライト光学系およびディスプレイ
KR100789138B1 (ko) * 2001-09-05 2007-12-27 삼성전자주식회사 조명장치 및 이를 적용한 반사형 액정표시장치
CN1307475C (zh) * 2003-04-08 2007-03-28 明基电通股份有限公司 中空式背照光组件
JP2005353599A (ja) * 2004-06-11 2005-12-22 Valeo Vision 光ガイドを有する自動車用の照明装置または信号装置
EP1939522A4 (de) 2005-08-17 2013-04-03 Fujifilm Corp Flächige beleuchtungsvorrichtung
US8405796B2 (en) 2008-07-14 2013-03-26 Sharp Kabushiki Kaisha Illumination device, surface light source device, and liquid crystal display device
JP5184445B2 (ja) * 2009-06-19 2013-04-17 シャープ株式会社 光源モジュール、及びそれを備えた電子機器
JP5087148B2 (ja) 2011-02-04 2012-11-28 株式会社東芝 液晶表示装置
US20130050615A1 (en) * 2011-08-23 2013-02-28 Sharp Kabushiki Kaisha Local dimming backlight unit and display device incorporating same
CN102661529B (zh) * 2012-04-05 2014-06-25 深圳市华星光电技术有限公司 背光模组及液晶显示器
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JPH06102414A (ja) 1994-04-15
EP0520623A1 (de) 1992-12-30
DE69222572D1 (de) 1997-11-13

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